COMMUNITY FORUM

Noisy Return Duct Work

We have a very noisy return on our duct work after having a new central air conditioner installed. There is a loud banging noise when the unit comes on and shuts off. Suspect this is a vacuum problem which rattles the duct work because the loudest bang comes after the unit has been off several minutes. What can be done? The return in on the second floor near the bedroom and is very annoying.

Metal duct expands and contracts as it is heated and cooled from operation. I wonder if it is not the duct work popping because a support has come loose. Metal duct work will transport noise long distances so it may be coming form the return on the side of the furnace. Go down to the unit and when it shuts down see if the noise is louder. If you have exposed ducts gently push on the large duct work and see if you can make it pop or make a noise similiar to what you are hearing. And if it is a new system get the dealer out there to solve it.

If you still haven't had any success, try this. Open the cover of the return and remove the filter. (I assume that's where the filter is) Try to determine if the duct work in that area is tight and sturdy by pressing on it with your hands. If you can find any sheet metal that is not firmly in place, you may be able to simply screw or nail it to an adjoining stud.Also try to recreate the failure while watching and listening into this "hole". You might get a clearer idea where the source of the problem is.